Camshaft adjusters are used in internal combustion engines to vary the timing of the combustion chamber valves, in order to be able to structure the phase relationship between a crankshaft and a camshaft variably within a defined angular range between a maximally advanced and a maximally retarded position. The adaptation of the valve timings to the actual load and rotation speed reduces fuel consumption and emissions. To this end, camshaft adjusters are integrated in a drive train via which a torque is transmitted from the crankshaft to the camshaft. This drive train may be formed for example as a V-belt, chain or sprocket drive.
In a hydraulic camshaft adjuster, the output element and the input element form one or more pairs of pressure chambers which act against each other and can be loaded with hydraulic medium. The input element and the output element are arranged coaxially. The filling and evacuation of the individual pressure chambers creates a relative movement between the input element and the output element. The spring, acting rotationally between the input element and the output element, forces the input element into an advantageous direction relative to the output element. This advantageous direction may be the same as or opposite to the twist direction.
One design of hydraulic camshaft adjuster is the vane adjuster. The vane adjuster has a stator, a rotor and a drive wheel with external toothing. The rotor is configured as an output element which can usually be connected rotationally fixedly to the camshaft. The input element contains the stator and the drive wheel. The stator and the drive wheel are connected together rotationally fixedly, or alternatively are configured integrally with each other. The rotor is coaxial to the stator and is arranged inside the stator. The rotor and the stator, with their radially extending vanes, influence oil chambers which act opposite each other, can be loaded with oil pressure and allow a relative rotation between the stator and the rotor. The vanes are formed either integrally with the rotor or stator, or are arranged as “push-fit vanes” in grooves of the rotor or stator provided to this end. Furthermore, vane adjusters have various sealing covers. The stator and the sealing cover are secured to each other via several screw connections.
Another design of hydraulic camshaft adjuster is the axial piston adjuster. Here a slider element is moved axially via oil pressure, and via oblique toothing causes a relative rotation between an input element and an output element.
A further design of camshaft adjuster is the electromechanical camshaft adjuster which has a three-shaft gear mechanism (for example a planetary gear mechanism). One of the shafts forms the input element and a second shaft forms the output element. Via the third shaft, rotational energy can be supplied to or discharged from the system by means of an actuator device, for example an electric motor or a brake. A spring may also be arranged which supports or returns the relative rotation between the input element and output element.
EP 1 571 301 A1 presents a camshaft adjusting arrangement wherein different power sources are provided for each of two camshafts.
DE 10 2010 000 047 A1 discloses a valve control device with an input rotor which rotates with a crankshaft, an output rotor which rotates with the camshaft, a planet wheel which executes a planetary movement to adjust the rotational phase between the camshaft and the crankshaft, a motor shaft which rotates for controlling the planetary movement, a cylindrical planet wheel carrier which carries the planet wheel and is connected to the motor shaft such that the planet wheel executes a planetary movement, and a lubricating device. The lubricating device has an infeed opening which emerges on a side face of the second rotor which lies axially opposite the planet wheel carrier. The infeed opening extends over an outer bearing face and an inner connecting face. Lubricant is conducted to the first rotor via the infeed opening.
DE 10 2013 003 556 A1 describes a variable valve timing control device. This has an input-side rotary component, an output-side rotary component positioned coaxially with a rotation axis of the input-side rotary component, at least one plate, a plurality of separating regions with a fluid chamber formed between the separating regions, a slider region which is fitted into the fluid chamber for relative rotation of the input-side rotary component and the output-side rotary component within a movement range thereof, a limiting mechanism for limiting a relative rotational phase, a fixing component which fixes the plate and separating region of the input-side rotary component, and a reinforcing component which is in engagement with the one of the separating regions having a contact surface, wherein the contact surface is formed to receive a contact of the slider region when the relative rotational phase is either a maximally retarded angular phase or a maximally advanced angular phase.